I've seen internal storage chain for quite some time. I had a pmg4 awhile ago in fwtdm and plugged into my service machine, while tying to figure out where the heck that os install disc was. it wasn't in my service drive's optical tray. finally realized it was in the other mac.
I don't know if that extends to firewire ports or not. I would expect ALL attached storage to show up over target mode... thunderbolt, usb, ide, sata, esata, pcmcia, cardbus, flash drive, firewire, etc.
